Many non-native plants and animals have been introduced to St. John over the history of human habitaion. Some of these plants and animals have become invasive. They destroy habitat, cause erosion, outcompete or predate native species, severely impacting or destroying local populations.
None of the deer, goats, sheep, cows, donkeys, cats, dogs, mongoose, rats, or pigs found on St. John today are native species. People brought them here as pets, for agriculture, or as pest control. Some of the animals arrived by accident as stowaways in cargo brought to the island or as pets and domestic animals left to run wild.
Today, these animals can severely impact native plants and animals. Mongoose are aggressive predators that feed on birds, reptiles, turtle eggs, and visitors' lunchboxes. Goats, deer, and donkeys feed on native vegetation, and they can also spread seeds of invasive plants. Pigs uproot plants and can be aggressive toward humans.
The NPS works to control these nonnative species in order to protect the landscape and sensitive species found here. To find out more about the park's efforts to control nonnative species, check out these documents.
Did You Know?
There are three species of lizards found on St. John. The iguana, which is not a true lizard, are vegetarians and are often found in trees. When threatened, they escape by dropping to the ground or into water. They can fall 40-50 feet to a hard surface without injuring themselves.